This invention relates to an oxygen-consuming composition for removing oxygen from the air in a closed space by chemical reaction. More specifically, this invention relates to an oxygen-consuming composition which contains a dithionite as the active oxygen-consuming component. In particular, this composition is advantageously used for controlling the storage environment of various articles which are susceptible to oxidative effects, including the propagation of aerobic microorganisms, such as fungi, by providing the composition in a confined container holding the articles to thereby significantly reduce the oxygen content of the interior atmosphere.
It is known that dithionites are capable of reacting with oxygen in the air and thus consuming the oxygen. However, the rate of this reaction is slow and dithionites are thus not well adapted for the purpose of removing oxygen rapidly. Hence, dithionites have not been used as an industrially advantageous anti-oxidant agent.
One of the major problems in storing and transporting articles or products susceptible to oxidative deterioration is how to remove the oxygen from packages for such articles to prevent such deterioration, either directly by oxidation of the products themselves or indirectly as by proliferation of fungi. As is common knowledge, many products lose commercial value through gradual deterioration by the influence of oxygen when left in the open air, irrespective of whether they are of organic or inorganic nature. If an article is easily susceptible to oxidation, it is readily converted into an oxidized product by oxidation with oxygen in the air. Even if the article is fairly resistant to oxidation directly, its commercial value will be lowered by proliferation of aerobic fungi, which grow well in the presence of oxygen.
Among the previous proposals for preventing oxidative deterioration of such articles involves packaging the same in a container of aluminum foil or plastic film with the air in the package being evacuated or replaced by carbon dioxide or nitrogen.
However, such a packaging method requires large scale equipment and is expensive. It also fails to prevent deterioration of the articles by the oxygen which gradually penetrates through the package walls because the aluminum foil or plastic film cannot exclude oxygen completely. Such problems of deterioration of articles during storage, transportation and packaging could be substantially alleviated if a simple and effective means can be provided to remove oxygen from the air present in a closed space, but so far this has proved a difficult goal to achieve in practice.